Field of the Invention
The present invention relates to a method for producing a lens mount and a lens mount that can be fixed radially in a lens tube.
Description of the Background Art
Lens mounts serve for retaining optical lenses in a precise mechanical manner in specific positions within a lens system, i.e. at a certain distance from one another and orientation in relation to one another, which can be described by the axial distance between the main points of the lenses and the radial distance thereof from an optical axis of the lens system. In particular in high-performance lens systems, however, it is possible for even slight positional deviations of individual lenses of the lens system to result in undesired system errors.
In lens systems, the individual lenses are arranged in relation to one another, usually directly or indirectly via a lens mount, within a lens tube, also referred to as a lens barrel.
The radial deviation of the position of the main points of the lenses from the optical axis of the lens system, said optical axis being formed in practice by the mechanical axis of the lens tube, is often kept to a low level via low-tolerance clearance fits between the lens mounts and the lens tube and axial bracing of the lens mounts in relation to one another.
In other solutions, which require greater outlay in respect of production and assembly, the lens mounts are fixed radially in relation to the lens tube, possibly following prior radial adjustment.
Plate-like filter holders which are intended for optical filters for cameras and are disclosed in laid-open application US 2013/0272689 A1 have, on both end sides, respectively matching clamping elements, by which they can be connected to one another, or to parts of the camera, along the optical axis of the camera. The connection allows rotation of the filter holders around the optical axis, radial play being suppressed. For this purpose, matching, resilient bearing elements and circular, centering guide grooves are provided on the mutually opposite end surfaces. Precise radial adjustment is not necessary here.
A radially adjustable lens mount is described in laid-open application DE 27 31 273 A1. The lens mount is accommodated in a sleeve-like ring and has, on its cylindrical lateral surface, three adjacent tangential flattened portions and, diametrically opposite, an elevation. Protuberances are arranged at equal intervals on the inner surface of the ring. Rotation of the lens mount in relation to the ring alters the position of the flattened portions and of the elevation in relation to the protuberances, and this allows radial displacement of the lens.
DE 37 30 094 C2 describes an apparatus in which an auxiliary mount, which can be displaced radially in a main mount, is pushed onto a base surface indirectly by an axially acting spring force. Two excentrics, which are mounted in a rotatable manner on the main mount in a state in which they are offset through 90° in relation to one another, and opposite compression springs are provided for radial displacement. Within the context of the present invention, it is possible to understand the main mount as being a lens tube and the auxiliary mount as being a lens mount.
FR 2 428 852 A1 describes a mount assembly in which a lens mount and a lens tube have arranged between them spring elements which give rise to a more or less uniformly distributed radially acting spring force between the lens tube and the lens mount and retain the lens mount with centering in the direction of the axis of symmetry of the lens tube. This spring force can be generated by differently configured spring rings, which enclose the lens mount virtually entirely, or by a multiplicity of individual spring elements, such as compression springs or leaf springs.
The two aforementioned mount assemblies comprise separate flexible elements with which the lens mount, in which a lens is mounted, can be fixed in a radially play-free manner within the lens tube. The axial positioning of the lens mount in the lens tube is predetermined by the defined position of the flexible elements within the lens tube.
DE 100 42 844 C1 discloses a lens mount which is formed by a mounting ring and a multiplicity of inwardly directed leaf-spring elements which are formed monolithically on the mounting ring and have their free ends engaging in an annular groove formed on the circumferential surface of a lens. The lens can be adjusted radially within the lens mount via on at least two threaded pins, which act at the free ends of the leaf-spring elements and are mounted in the mounting ring. If the lens mount has been fixed in a lens tube, it is thus also possible for the lens to be adjusted radially, and fixed, in relation to the axis of symmetry of the lens tube. The fixing of such a lens mount in a lens tube is achieved usually via an axial force fit, e.g. by means of a retaining ring. A fundamental disadvantage of this fixing method is that it may result, e.g. as a result of impact loading, acting counter to the static friction, in play-delimited, irreversible radial displacement of the lens mount within the lens tube.
In comparison with the aforementioned lens assemblies, there is advantageously no need here for any additional clamping elements, but the functioning of the lens mount requires the latter to have a considerable radial extent, for which the necessary amount of installation space is not always present.
A further possibility for monolithic clamping elements is disclosed in respect of an eyepiece assembly which has diopter adjustments and is disclosed in laid-open application DE 10 2008 028 720 A1. For the diopter adjustment, an optical element accommodated in a mount is displaced along the optical axis. The mount and a mount-accommodating sleeve have provided between them frictional elements, which generate a minimum moment which has to be overcome and which makes it more difficult for the mount to be displaced in an undesired manner. In one embodiment, the frictional elements are generated by parts of the mount, which butts against the sleeve, containing slots and by resulting resilient fingers being spread apart by a spring element inserted therein. The invention realizes the object of adjusting the optical element axially. However, it is not suitable for radial adjustment.
A monolithic optical mount disclosed in DE 10 2008 063 223 B3 comprises a fixed outer mounting ring and a radially adjustable inner mounting ring. The mounting rings are formed by separating material cutouts and are connected only via remaining crosspieces. Corresponding to the crosspieces, which are arranged in a uniformly offset manner in relation to one another, the outer mounting ring has manipulator units, which act radially on the inner mounting ring. Manipulator units, in the simplest case, are threaded pins, which counteract springs on other manipulator units. This embodiment of the optical mount has the same disadvantages already explained in relation to DE 100 42 844 C1.
A multiplicity of further lens mounts in which the lenses are retained within the lens mount via flexible elements which are formed within a mounting ring so as to be connected monolithically thereto are known. Lens mounts in which flexible elements are formed on the circumference of a mounting ring and are connected monolithically to said mounting ring are not known.